A wire rod rolling mill generally comprises a plurality of roughing stands, a cropping shears, a finishing block, a coiler (e.g. a coil-laying cone) with a coiler pipe (e.g. a coil-laying pipe) and a coiler with a coiler pipe and a coiler drive comprising a coiler motor and a coiler gear unit and a delivery conveyor for the coils of wire or rod.
The previously mentioned components of the wire rod rolling mill are arranged in succession in the wire running direction and the wire rod rolling mill can also be provided with a controller which incorporates a computer. The computer controls the cropping shears according to a predetermined rolling program by a computer showing command and the shearing unit cuts away a cropped length according to the computer shear command from the leading end of a rolled wire rod workpiece upstream of the entrance of the rolled wire rod workpiece into the finishing block (i.e. the finishing mill with a multiplicity of mill stands) and thereby produces the wire head in a wire to be deposited in a coil and the cropped length is described. As expressly emphasized once more the shearing unit ahead of the finishing block cuts off the leading end of the rod before it enters the coil-laying pipe. The delivery conveyor chiefly comprises a plurality of parallel traction elements. It can also be constructed as a roller bed.
A wire rolling mill in which the cropped length is not correlated with the position of the coiler pipe, can operate with high rolling speed
The separation of a cropped length upstream of the finishing block is required in this wire rolling mill because the leading end of the rolled wire rod workpiece which leaves the roughing stands has nonuniformities which shorten the life of the rolls or the caliber or sizing elements in the finishing block.
On the other hand there is a danger that the wire head provided to the delivery conveyor uncontrollably from the coiler can not be deposited without problems. That can lead to a completed rolled wire rod workpiece which can not be assembled into bundles and must be discarded as waste.
To avoid such problems, it was necessary, in the past, to have an operator at the coiler who can grasp the wire head with a tool and coil it so that a problem-free fanning out of the finished wire in distinct coil turns can be ensured
In investigations which are not part of the known state of the art, a computer for the computer shear command allowed for a time interval in which according to the size of the spacing between the cropping shears preceding the finishing block and the coiler the speed of the wire and the coiler pipe position is fixed and is selected so that the wire head can enter into a coiler pipe position sector on the delivery conveyor in which according to experience a trouble-free coiling and deposition of the wire head can be effected.
One should also consider the prior experiences described in German Patent No. 20 38 747 which were obtained in rolling mills with substantially slower roll speed in which the shearing unit could be positioned to the rear of the finishing block. In attempts to use the rolling mills which are known with a high roll speed the described problems occur in a statistical distribution. That is because of the statistical variations of parameters which the program with which the computer operates cannot allow for.